This invention relates in general to pneumatic tire pumps and in particular to a tire pump which can be mounted upon a vehicle wheel and driven by rotation of the wheel to supply air to a pneumatic tire.
Pneumatic tires are mounted upon vehicle wheels and form a portion of the vehicle suspension. The flexibility of the tire absorbs minor irregularities in the road surface while maintaining contact with the road surface. The contact area between the tire and the road surface is typically called the tire "footprint". Tire manufacturers have been known to cooperate with vehicle manufacturers to design unique tires for specific vehicles.
All pneumatic tires have a rated inflation pressure. Either overinflation or underinflation of a tire results in a reduced tire footprint. The reduced footprint results in additional wear of portions of the tire and reduces the service life of the tire. Additionally, low tire pressure increases the rolling resistance of the tire, causing an increase in fuel consumption. If the vehicle tires are inflated at different pressures, as would occur if one of the tires is soft, the handling of the vehicle is adversely affected. Accordingly, it desirable to maintain the correct inflation pressure in the vehicle tires.